Amb aquesta rutina treballo els músculs i la resistència.

Because treballo is the 1st person singular present form of treballar.

• treballar = to work
• treballo = I work / I train / I work on

In fitness contexts, treballar can mean to train or to work a part of the body:

• Treballo els músculs = I work/train the muscles

So even though the basic meaning of treballar is to work, in this sentence it naturally means I work on / I train.

Amb means with.

So:

• Amb aquesta rutina = With this routine

It introduces the means or method: this routine is what helps the speaker train the muscles and endurance.

English also often starts sentences this way:

• With this routine, I train...

So the Catalan structure is very natural.

Aquesta means this and it is the feminine singular form.

Catalan demonstratives change to match the noun:

• aquest = this (masculine singular)
• aquesta = this (feminine singular)
• aquests = these (masculine plural)
• aquestes = these (feminine plural)

Here the noun is rutina, which is feminine singular, so we use:

• aquesta rutina = this routine

In Catalan, nouns have grammatical gender, and rutina is feminine. That is why it takes:

• aquesta instead of aquest
• la if you use the definite article: la rutina

Many nouns ending in -a are feminine, though not all nouns follow simple patterns. In this case, you just learn rutina as a feminine noun.

Catalan often uses the definite article more than English does.

So:

• els músculs = the muscles
• la resistència = the endurance

In English, we often leave articles out in general statements, but Catalan commonly keeps them. This is especially normal when talking about body parts, general concepts, or things understood in context.

So treballo els músculs i la resistència sounds natural in Catalan, even if English might simply say I train muscles and endurance or I work on muscle and endurance.

Because the Catalan word is múscul in the singular and músculs in the plural.

• el múscul = the muscle
• els músculs = the muscles

This is different from English muscle / muscles. The Catalan plural keeps the -l sound:

• múscul → músculs

Also note the written accent in múscul.

I means and.

So:

• els músculs i la resistència = the muscles and endurance

It simply links the two things being trained.

It is related, but in this sentence resistència means endurance or stamina, not usually resistance in the English sense.

So in a fitness context:

• treballar la resistència = to train endurance / stamina

The word is cognate with similar Romance-language words, but you should choose the English meaning based on context. Here, endurance is the most natural translation.

This is the normal Catalan order:

• Subject is often omitted because the verb ending already shows who is doing the action.
• Verb: treballo
• Object: els músculs i la resistència

So the full structure is:

• Amb aquesta rutina = with this routine
• treballo = I train/work
• els músculs i la resistència = the muscles and endurance

Catalan often drops the subject pronoun jo because treballo already clearly means I work/train.

Yes, you could say:

• Amb aquesta rutina, jo treballo els músculs i la resistència.

But usually jo is unnecessary unless you want emphasis or contrast.

For example:

• Jo treballo els músculs i ell treballa la flexibilitat.
  • I train the muscles and he trains flexibility.

Without emphasis, Catalan normally leaves jo out.

Treballar is very common in fitness and body-training contexts. It often means:

• to work
• to work on
• to train

For example:

• Treballar els braços = to work/train the arms
• Treballar l'esquena = to work/train the back
• Treballar la resistència = to train endurance

Other verbs are also possible depending on context, such as entrenar (to train), but treballar is very natural here.

Catalan often expresses this idea with amb + noun:

• Amb aquesta rutina... = With this routine...

English might say:

• With this routine, I train...
• Using this routine, I train...

Catalan does not need a separate word meaning using here. Amb already expresses the idea of means or instrument.

A rough English-style pronunciation is:

ahm ah-KES-tuh roo-TEE-nuh truh-BAH-lyoo els MOOS-kools ee luh ruh-zees-TEN-see-uh

A few notes:

• amb: the b may sound soft or be barely heard in natural speech
• aquesta: stress on -ques-
• treballo: the ll is a special Catalan sound, often similar to a soft ly
• músculs: stress on the first syllable
• resistència: stress falls on -tèn-

Pronunciation varies somewhat by dialect, but this gives a useful starting point.

This sentence is a good example of several basic Catalan patterns:

1. Preposition + noun

   • Amb aquesta rutina = with this routine

2. Demonstrative agreement

   • aquesta matches feminine singular rutina

3. Present tense verb conjugation

   • treballo = I work/train

4. Omitted subject pronoun

   • no jo is needed

5. Use of definite articles

   • els músculs
   • la resistència

6. Coordination with i

   • els músculs i la resistència

If you understand all of those, you understand most of the sentence’s structure.